My husband recently bought us a Bruno mattress which he finds very comfortable and supportive but even with a topper it is still too firm for me. He says that coil sprung mattress are no good for side sleepers and therefore latex foam type better for us. Can we buy a zip link super King that will give us medium latex foam type on one side for him and a softer one for me? He is 15 stone and I am 9 stone.Thank you